1. Field of the Invention
The present invention relates to buoys, large floating ocean platforms, and other smaller-scale floating platforms used to support various types of instrumentation and equipment.
2. Description of the Related Art
A need for stable platforms at sea is well established in the oceanographic research and energy production communities. However the types of platforms and the platform design options available to these communities are limited. For example, the commercial platforms available to oceanographers are generally large spar buoys that weigh thousands of kilograms, are on the order of 20 m long, and are very difficult to deploy and recover from conventional ships. Smaller buoys are available, however the smaller buoys generally have very limited stability and mast height, thus restricting the type of scientific instrumentation that can be effectively deployed on the buoys. Prior art patents related to small scale buoys include, for example, U.S. Pat. No. 4,949,643 to Bowersett et al. that discloses an anti-tilt buoy mooring system for use in oceanographic and military applications. The ""643 patent demonstrates the need for stabilizing buoys and is directed to stabilizing forces from mooring lines attached at the center of buoyancy of a standard, caisson type buoy. U.S. Pat. No. 5,348,501 to Brown discloses a compact retrievable marker buoy for marking underwater locations for recreational, scientific and other purposes. U.S. Pat. No. 4,962,798 to Ferraro et al. discloses a buoy deployment system for storing and deploying compact sonobuoys from an aircraft. The ""798 patent illustrates the need for compact buoys capable of housing sophisticated scientific instrumentation.
For large energy production platforms, e.g., oil platforms, choices are typically limited to seafloor mounted, shallow-water jack-up towers, or floating barge or large spar exploration/production platforms. In deep-water offshore locations, it becomes impractical to establish seafloor-based platforms as a means to support an exploration/production facility above the water. Floating barge type platforms, however, have difficulty operating in a variety of sea-states and currents, while simultaneously maintaining contact with subsurface oil production equipment. Alternatively, production facilities have been designed for positioning directly on the ocean floor. Many of the facility designs in this category, however, are complex and difficult to construct and maintain. Spar-type platforms are typically very large (e.g., hundreds of thousand of tons and 100""s of feet high), need to be fabricated in specially designed docks, require extreme measures to tow them into place, and are very expensive to construct (many such platforms cost more than $1 billion). The use of such large and expensive spar platforms is thus confined to applications that have a very high return on investment.
U.S. Pat. No. 3,572,041 to Graaf describes details of an oil rig production platform according to the prior art, including a massive spar section of unitary construction. U.S. Pat. No. 4,702,321 to Horton illustrates a spar structure comprising an elongated cylindrical caisson having a length over 200 m, the caisson being again of prefabricated unitary construction that must be towed to a work site.
Other designs exist concerning stabilizing large oil platforms in ultra deep water (over 600 m deep) where conventional catenary mooring lines become impractical. U.S. Pat. No. 6,012,873 to Copple et al. discloses a buoyant spar platform with a retractable gravity base. The gravity base is tethered with pre-tensioned cables to the buoyant spar structure and is designed to minimize the platform""s response to excitation loads. In this design the buoyant spar structure is also a large prefabricated unitary structure.
The above-mentioned patents show a market need for stable, sea-going platforms. Further, there is a need for more compact platforms, regardless of scale, that would reduce the costs of transporting the platforms to and from a work site, and also reduce the costs of deploying and recovering the platforms at a work site.
The present invention is directed to an improved, highly stable, sea-going platform. An object of the present invention is to provide a platform that is compact in a stowed configuration for ease of transport, and that extends upon deployment to a length that increases the platform""s deployed stability. Another object of the present invention is to provide a platform that is easily deployed and recovered. Yet another object of the present invention is to provide a platform design that is highly scalable, from large ocean going platforms used for energy production, to small lake-based platforms used to support small-scale instrumentation.
According to the present invention, a telescoping spar structure includes a platform/hull for supporting a payload; a telescoping spar attached to the platform/hull that includes several interlocking tubes extending from a shallow end to a deep end of the spar, the tubes configured to telescope in and out of adjacent tubes such that the tubes are nestable together in a stowed configuration; a buoyancy chamber attached to the spar between shallow and deep ends of the spar; and, a damping chamber attached to the spar between the buoyancy chamber and the deep end of the spar, the damping chamber including: a first compartment for entraining a volume of water, a second compartment for enclosing deployment ballast, and a release mechanism for jettisoning the deployment ballast from the second compartment after the spar structure is deployed.